Process and apparatus for subliming sulphur



Nov. 17, 1931. 1.. GILLETT 1,832,013

PROCESS AND APPARATUS FOR SUBLIMING SULPHUR Filed June 30, 1926 2 Sheets-Sheet l INVENTOR 40W?! 6/4457? Nov. 17, 1931. GILLETT PROCESS AND APPARATUS FOR SUBLIMING SULPHUR Filed June 30, 1926 2 Sheets-Sheet 2 3 4 SULFUR INVENTOR LOW/W 6/4457?" ATT Patented Nov. 17, 1931 UNITED STATES PATENT OFFICE LOWRY GIIJIET'I, OF ossn'rr. NEW YORK, ASSIGNOB 1'0 GENERAL CHEMICAL COK- YORK, N. Y, A CORPORATION OF NEW YORK PROCESS AND APPARATUS FOR SUBLIMING SULPHUR Application fl ed Inn: 80, 1988. Serial No. 119,532.

This invention relates to a process and apparatus for subliming sulphur. It has for its object to provide a novel method, whereby sulphur may be sublimed with greater efliciency than heretofore and wherein the sublimation is subject to very close control, and to provide an apparatus novel in construction an economical in operation for practicing this novel method. Other objects will appear from the description hereinafter.

In the accompanying drawings Fig. I is a sectional elevation of m novel apparatus on a line a-a of Fig. II. ig. II is a plan view of the apparatus and Fig. III is a graphical re resentation of the relation of theratio of suhlimed to burned sul bar and the time of contact of air with sulp ur as hereinafter explained in connection with carrying out my novel process.

Referring more particularly to the various parts of In novel apparatus as shown in the drawings the raw sulphur is supplied by any suitable means (not shown) to the vertical standpipe 10. At the lower end of the standpipe is a bustle pipe 11 weldedthereto,

roviding an air poc et 11' about the sulphur insaid standpi e. Extending through the bustle pipe 11 1s a flanged pipe fitting 12 through which air may be admitted. The bustle pi e is also provided with a peep-hole 13 to ena Ie the operator to easily ascertain whether the sulphur is bein properly delivered to the standpipe. At t e bottom of the standpipe 10 and connected therewith is a conduit 14, one end of which is suitably attached to a shell of the sublimer 15 in gastight relation. In the conduit 14 is a screw conveyor 16 mounted on shaft 17. The shaft is carried by a bearing 18 mounted on the opposite end of the conduit and passes through a suitable packing means 19 which serves to prevent gas leakage. The conveyor is driven in any conventional manner as by means of a pulley 20 fastened on shaft 17 and connected by means of a belt 21 with a source of power, as for example a motor 22 supported on the channels 23. In any case the speed at which the conveyor is driven is regulated to deliver the required amount of sulphur to the sublimer 15.

plolyled the structure of the o The sublimer may be constructed of any suitable material resistant to the action of sulphur. As shown in the drawings, there is provided an outer shell 25 of steel or other material and a lining 26 of fire-brick or the like. The preferred form of sublimer is cylindrical and is provided with an arched roof 27 of fire-brick or the like, covered with insulating material 28.

The sublimer is provided with a plurality of tubes 30 of suitable material such as wrought iron, which pass through the openings 31 in the walls. The tubes are so directed as to extend beneath the surface of the melted sulphur and near to the bottom of the sublimer. At its outer end each tube is provided with a flange 32 secured to a flanged pipe fitting 33 which is in turn welded or otherwise suitably secured to the shell 25. Attached to the flange 32 of the tube 30 is a Y-pipe fittin 34 providing an air inlet through the ranch 35 and an inspection opening through the branch 36. The air inlet 35 may be connected to a suitable air suppl line 43 provided with a valve 37 for contro lin the amount of air admitted.

it the inner end of each tube 30 is a bellshaped air distributing. member 38. This member is of a suitable foraminous structure and as shown for example, is open at the bottom of the bell and is provided with a plurality of vertical slots 39 to uniformly distribute the air in fine streams to the melted sulphur. By introducing the air through a downwardly directed o ening, thus causing the initial direction 0 movement of the air to have a downwardly directed component, and by providing for subdivision of the air stream into a lurality of small streams, the complete utllization of the air within the body of melted sulphur is aided, and this is of considerable importance as more fully pointed out hereinafter. If desired, each tube 30 may be provided with a plurality of these bell-shaped air distributing heads connected thereto by suitable pipe connections. It will be noted that where a single distributing member for each tube is emning 31 is suc as to permit the removal 0 the air supply tube and distributing head without disassembling. The opening 36 in the Y-pipe fittin provides a means whereby obstructions in the air tube or distributing head may be easily removed.

In the side walls of the sublimer are provided the openings 40 through which the gas comprising the sulphur dioxide and sublimed sulphur may ass to a combustion chamber or the like. 11 practice usually but one of the openings is connected to the gas line while the other which ma serve as an inspection opening is closed y a suitable plate or door.

Near the bottom of the sublimer are rovided openings 41 whereby access may be ad to the interior of the sublimer for the purpose of cleaning and through which the ash and other foreign matter may be removed. Each opening is closed by means of fire-brick and a pll ate 42 of steel or the like.

he general operation of my; apparatus is as follows. In starting up t e sublimer a small quantity of sulphur is fed in through the standpipe 10 and conveyor 16. This sulphur is ignited by a gas torch or other means through one of the outlets 40 which is not connected to the exit s line and is normally closed. Air, an oxi izing gas is admitted through this opening to support the combustion and asit proceeds more sulphur is fed in until the level of the melted sulphur rises above the air distributing heads 38. Air is then admitted through the tubes 30 and the distributing heads, and the opening 40 is closed. The sulphur feed is continued at a rate greater than normal until the melted sulphur rises to a predetermined level for normal 0 eration. The sulphur and air feeds are then regulated so as to maintain this level of sulphur i. e. so as to replenish the body of sul hur in the sublimer as sulphur is burned an sublimed therein and to admit air at a predetermined rate.

It is well known that the oxidation of sulphur to sulphur dioxide is a highly exothermic reaction. Attempts have been made heretofore to employ this large amount of heat developed in the oxidation of sulphur to cfl'ect the sublimation of a considerably greater quantity of the sulphur. Certain of these attempts have been directed to drawing or forcing a limited ergiantit of air over the surface of the melt sulp ur whereb oxidation occurs and the cat is develo at or above the surface of he sulphur, w 'le certain other attempts have been directed to atomizing or sprayin melted sulphur with a limited amount of air and thereby subliming a substantial proportion of the sulphur spray. All of these methods of the prior art are highly ineflicient for the purpose of subliming the sulphur and have the obvious disadvantage that the heat is develo ed above or at the surface of the melted su phur and is dissipated by radiation or as sensible heat in the w ereby its eflect for subliming is lost. Con uently a considerably larger volume of air t an is theoretically necessary to oxidize and sublime all the sulphur is em- Eioyed and the amount of sulphur which may sublimed with a given amount of oxidation is comparatively low.

By my novel process and apparatus I have provided a method whereby the heat prouced by burning a portion of the sulphur is liberated internally of the body of melted sulphur whereby substantially all the heat of reaction is conserved and serves to sublime the largest possible amount of sulphur with a minimum of oxidation. Furthermore it is to be noted that my method, by increasing the proportion of sublimed sulphur to burned sulphur, provides for a substantial decrease in the amount of impurities in the final sulphur dioxide gas produced since the sublimed sulphur carries with it a very much less amount of impurities than the sulphur dioxide gas produced by burning, and there is much less entrainment of foreign matter in the exit es from the sublimer due to the very muc lower volume of air necessary to be introduced into the sublimer to carry out my novel sublimation process than is required for complete bumn carrying out my process as for example in the ap aratus disc osed air is admitted through t e air tubes 30 and distributing heads 38 to the bottom of the sublimer where it is uniformly distributed and passed up through the body of the melted sul hur in fine streams. The pressure differential, that is the diflerence in pressure between the atmosphere above the melted sulphur and the pressure in the air supply line, is maintained at a value necessary to give a predetermined rate of flow of air with reference to the head of melted sulphur. It will be appreciated that as the head of sulphur is varied this will vary the time of contact of the air passing through the sulphur. Also the size of the bubbles of air and the viscosity of the melted sulphur influence the time of contact of the air with the sulphur. I have discovered that this rate of air flow, determined with reference to the depth of sulphur, or more specifically the time of contact of the air with the melted sulphur, may be so regulated that substantially all of the oxygen in the air admitted is used up in the oxidation of the sulphur before it reaches the surface. Under such conditions the heat liberated by the exothermic reaction is developed almost entirely within the body of the melted sulphur. This mode of operation permits of a maximum conservation of the heat of reaction for the purpose of subliming the remaining sulphur or the ratio of sublimed sulphur to Ill neaaom burned sulphur increases and approximates the theoretical maximum value.

The air in passing up through the melted sulphur will, of course, cause a boiling effect upon the surface, the extent of such action depending considerably upon the rate of air flow. The amount of air introduced through a single air tube should preferably be adjusted so that a too violent boiling will not occur, as, if a violent boiling is permitted to exist, a considerable proportion of the free oxygen in the air or other oxygen bearing gas may escape into the space above the melted sulphur, instead of being utilized to generate heat within the body of the sulphur. It is clear that while I have shown but two air tubes 30 in the drawings, this disclosure is for purposes of illustration only and the number of tubes or the area of the air distributing heads may be increased for any required air supply so that the rate of air flow upwardly through the sulphur at any point will not be so great as to cause too violent agitation of the surface. The formation of spray, as the result of violent boiling, is to be avoided as it may result in impurities from the surface of the sulphur being carried out of the chamber in the gases and thus negative one of the chief advantages of sublimation; i. e., the production of a pure gas. To provide for the operation of the sublimation process at maximum efliciency, it is necessary to regulate the variables under the control of the operator in such a manner that the time of contact of the air with the melted sulphur is above a minimum limiting value which may vary with the type of air distributing means as hereinafter pointed out. The controllable variables comprise for example the rate of air feed, head of sulphur above the air inlet, sulphur fed per unit time, temperature of air admitted, etc. The proper relation of these factors may be determined by varying one while maintaining the others constant. For example, if a certain output from the sublimer is desired, that is, if the feed of sulphur is fixed then as the depth or head of sulphur in the sublimer is increased, it is found that the amount of air admitted may be simultaneously decreased up to a point from whence it remains substantially constant. At or above this head of sulphur the amount of air being admitted is at a minimum for a given quantity of sulphur sublimed and burned, indicating substantial- 1y complete utilization of the oxygen of the air internally of the melted sulphur whereby a maximum conservation of the heat of reaction is obtained.

As another example, maybe given the condition where a given head of sulphur is maintaiued constant. Assuming now that an excessive amount of air is introduced, the ratio of sublimed to burned sulphur will be below the maximum, indicating that a substantial amount of combustion is taking place above the surface of the sulphur and that the heat of combustion is not being efliciently utilized to sublime sulphur. If new the air supply is graduall reduced the amount of combustion takin p ace above the sulphur will decrease, and the above ratio will gradually increase until a point is reached at which the ratio reaches its maximum value, and then afurther reduction in air supply results in no increase in the ratio. At or below this air suply value substantially all of the oxygen is )eing consumed within the body of the sulphur. In other terms, under these conditions the maximum amount of sublimation is taking place with a minimum amount of oxidation, or the sublimer is operating at a maximum efiiciency. Similarly, by fixing any one of the several variables in operation, one may adjust the remaining variables in accordance with my disclosure so as to maintain a time of contact of the air with the sulphur which is sutiicient to obtain the maximum amount of oxidation internally of the melted sulphur, thereby conserving and utilizing the heat developed most etliciently for the purpose of sublimation. Fig. 111 represents the relation of the ratio of the sublimed to burned sulphur and the time of contact of the air with the melted sulphur for a given quantity production. As may be seen, there is a definite value of time of contact of the air with the sulphur, as determined largel by the head of sulphur above the air inlet, elow which the efliciency of the sublimation process falls rapidly. The absolute value of the time of contact of the air with sulphur may vary with the specific type of apparatus, etc., as pointed out, but the relationship remains substantially the same for each case. It is the purpose of my invention to determine this value for each type of apparatus and to control the variables so that the subliming operation is carried on above this limiting value.

I have found that under properl controlled conditions the temperature of the gaseous products of the sublimation recess will be below the boiling point of su pliur, 832 F. During operation of m sublimcr, I have found the temperature at the outlet to be approximately 700 F. If the outlet temperature should rise above the boiling point of sulphur, this would indicate that a substantial amount of combustion is taking place above the surface of the sulphur and that a portion of the heat generated is being used to raise the sensible heat of the gases and not to sublime sulphur. Accordingly, this may be taken as a convenient means of determining the maintenance of proper operating conditions.

The means and method of introducing the air into the sulphur considerably affect the regulation of the variables heretofore referred to. It is, of course, desirable to introduce the air as uniformly as possible throughout the body of melted sulphur and to provide for maximum contact by causing the gas to enter the sulphur in very fine streams. If 5 the streams of air are lar e and not well distributed it will be fouri necessary to vary the other controllable factors, for example to increase the depth of the head of sulphur for a given amount of air being admitted, to offset this condition. However, for any s ecific type of air distributing means the ot er controllable variables may be so regulated as heretofore set forth as to produce a maximum amount of sublimation with a minimum amount of oxidation.

I have found that by proper regulation of the variables so that the time of contact of the air with the sulphur is such that substantially all of the oxygen of the air is used up'in the formation of sulphur dioxide internally of the body of the melted sulphur, I am able to sublime'from S t-86% of the sulphur with an oxidation of only 14-16%. It is therefore clear that my process provides for a much greater efficiency in operation than has hitherto been considered possible.

It is to be noted that substantially all air is excluded from above the surface of the melted sulphur, the entire supply being obtained by means of the air tubes 30. This I consider of great importance as it permits a very much better control of the amount of air bein admitted and also of the temperature in 518 sublimer and of the gases leaving the same. It also serves to prevent any substantial oxidation at or above the surface of the sulphur with the accompanying loss of heat and thereby provides for maximum eifi- -cciency in operation. It is also to be noted that the admission of any extraneous gas into the chamber is entirely avoided.

It is preferable, especially where the producis of the sublimer are to be used in the roduction of en] huric acid, or where S 2 is ultimately pro need, that the process be carried out under a positive pressure, i. e., a pressure above atmospheric. This permits a maximum control. of the air fed into the sub limer and tends to a greater efficiency and economy in operation. The gas required to be compressed for passage through the sublimer is only about 15% of the total air required by the system for complete oxidation of the sulphur. This obviously very substantially reduces the size and cost of operation of the blowers or compressors. This feature however is not necessary and I do not wish to limit myself to this method of operation except as defined in the appended claims.

I have shown in the apparatus disclosed a suitable means for the prevention of gas leakage through the sulphur feed where it is desirable to operate the sublimer under positive pressure. This comprises the gas-tight bustle pipe 11 and air inlet 12. The inlet 12 15 connected with a convenient source of air supply which is maintained at a positive pressure just equal to or slightly above that pressure maintained in the sublimer. This construction and operation provides an air pocket 11 in the bustle pipe 11 and prevents leakage of the gaseous products from the sublimer. By proper regulation of the pressure of this air supply as indicated, substantially no air (less than 3%) is admitted to the sublimer through this means, thereby accom lishing the urpose heretofore mentione viz, to exc ude air from the surface of the melted sulphur.

While I have heretofore in the description of my process, referred to air as the means for obtaining oxidation of the melted sulphur, I do not wish to limit my recess to the use of this medium but inclu e also within the terms employed any gaseous oxygen containing composition, as for example commercial oxygen or oxygen enriched air, which may be used, with their well-known accompanying advantage.

It will be evident to one skilled in the art that the temperature of the melted sulphur should be maintained above the dash point of the sulfur and whenever I have referred to melted sulphur throughout the specification and claims I refer to melted sulfur above this temperature.

The products of the sublimer may be used for the purpose of enrichin the burner gas from an ordinary Herreschofl roaster in which case they are passed directly from the sublimer into the lines from such roasters and are burned with the oxygen carried by such burner gases. If it is desired to produce sulphur dioxide gas directly for the manufacture of sulphuric acid, liquid sulphur dioxide, etc., the products may be passed to a suitable combustion chamber where they are mixed with oxygen or air and burned. Furthermore, the products of the sublimer may be cooled in the absence of air to produce refined sulphur products such as flowers of sulphur, roll brimstone, etc., more econimically than in the present method of manufacture.

Various changes may be made in the specific form of appartus shown and described, and in carrying out my novel process, without departing from the'spirit of the invention and I do not wish to limt the scope thereof except as defined in the appended claims.

I claim:

1. The process of subliming sulphur which comprises maintaining a body of melted sulphur in a container, substantially excluding presence of free oxygen above the surface of the sulphur and introducing a regulated limitcd quantity of an oxygen containing medium below the surface of the sulphur.

2. The process of subliming sulphur which comprises maintaining a body of melted sulphur in a container, substantially avoiding the introduction of air to the interior space of the container above the surface of the melted sulphur, and introducing a limited quantity of air below the surface of said melted sulphur.

3. The process of subliming sulphur whlch comprises introducing a limited quantity of air beneath the surface of a body of melted sulphur and maintaining the head of melted sulphur above the air inlet such that there is substantially complete utilization of the oxygen of the air introduced before said 8.11 reaches the surface of the sulphur.

4. The process of subliming sulphur wh1ch comprises passing an oxygen containing gas through a body of melted sulphur under such conditions of time of contact of the gas with the melted sulphur that there is substantially complete utilization of all the free oxygen present during the passage of the gas through said sulphur.

5. The process of subliming sulphur which comprises passing a limited quantity of an oxygen containing gas through a body of melted sulphur and utilizing substantially all the heat of reaction of a portion of the sulphur with the oxygen content of said gas, within the body of melted sulphur, to sublime the remaining portion of said sulphur.

6. The process of subliming sulphur which comprises passing an oxygen containing gas through a body of melted sulphur under such conditions of time of contact of the gas with the melted sulphur that there is substantially complete utilization of all the free oxygen 7 present during the passage of the gas through said sulphur, maintaining a relatively constant feeding of sulphur to the body of melted sulphur under treatment and controlling the admission of the oxygen containing gas into the body of the melted sulphur, so as to maintain a relatively constant head of melted sulphur.

7. The process of subliming sulphur which comprises maintaining a body of melted sulphur, introducing air below the surface of said sulphur, the direction of movement of said air at its point of introduction having a downwardly directed component. and substantially excluding the admission of air above the surface of said sulphur.

8. The process of subliming sulphur which comprises maintaining a body of melted sulphur, and introducing only such an amount of air beneath the surface of said sulphur as i will cause the gaseous products of the sublimation process to have a temperature below the boiling point of said sulphur.

9. The process of subliming sulphur which comprises maintaining a body of melted sulphur, introducing air beneath the surface of said sulphur, substantially excluding the ad mission of air above the surface of said sulphur, and proportioning the amount of air introduced beneath the surface of said sulphur in relation to the head of sulphur to maintain a temperature below the boiling point of said sulphur in the gaseous products of said rocess.

10. T e process of subliming sulphur which com rises maintaining a body of melted sulp ur, substantially excluding the admission of air above the surface of said sulphur, and introducing air beneath the surface of said sulphur in such amounts as to maintain a temperature of approximately 700 F. in the gaseous products of said process.

11. In an apparatus for subliming sulphur, the combination of a substantially gas tight container for enclosing a body of melted sulphur, said container being closed against the admission of extraneous gas thereinto and be ing provided with an outlet above the surface of the sulphur, means for feeding sulphur into said container, and gas distributing means constructed and arranged for introducing gas within the body of the melted sulphur in a direction having a downwardly directed component.

12. In an apparatus for subliming sulphur, the combination of a substantially gas tight container for enclosing a body of melted sulphur, said container being closed against the admission of extraneous gas thereinto and being provided with an outlet above the surface of the sluphur, means for feeding sulphur into said container, and gas distributmg means entering said container and terminating below the surface of the sulphur in said container, said gas distributing means being provided with a downwardly directed Opening under the surface of the sulphur and adjacent the bottom of the container, whereby oxygen-containing gas is introduced under the surface of the sulphur initially in a direction having a downwardly directed component.

13. Apparatus for subliming sulphur comprising in combination a closed container adapted to hold a body of melted sulphur, a gas outlet for the container positioned above the level at which the melted sulphur is maintained, a gas distributor head for introducing oxidizing gas into the melted sulphur adjacent the bottom of the body thereof in a multiplicity of fine streams, means for feed ing sulphur into the container, said container being of such capacity as to permit the mailitenance therein of :1 body of melted sulphur of such depth as to cause substantially complete utilization of the oxygen of the oxidizing gas within the body of melted sulphur.

14. A sulphur sublimer comprising in combination a container adapted to hold a body of melted sulphur. means for introducing an oxidizing gas below the surface level of the sulphur, said means having associated therewith means for distributing the gas in a multiplicity of initially downwardly directed fine streams, the said container being constructed so as to exclude the admis sion of extraneous gases from above the surface of the melted sulphur.

15. Sul hur subliming apparatus according to claim 13 in which the distributor head is downwardly directed and provided with vertical slots.

16. The process of vaporizing a vaporizable liquid which comprlses maintaining in a container :1 body ,bf the liquid having the essential properties of sulphur for operation, including that of subliming, substantially excluding from the interior 5 ace of the container above the surface 0 said liquid all substances chemically reactive therewith, and introducing into the body of said liquid below the surface thereof a substance which is chemically reactive therewith in such manner and in such amounts as to vaporize a substantial portion of the liquid by the heat of reaction of the substance with the reacting portion of the liquid.

In testimony whereof, I affix my signature.

LOWRY GILLETT.

6 sesame ing constructed so as to exclude the admission of extraneous gases from above the surface of the melted sulphur.

15. Sulphur subliming ap aratus according to claim 13 in which the istributor head is downwardly directed and provided with vertical slots.

16. The process of vaporizing a vaporizable liquid which comprises maintaining in a container :1 body of the liquid having the essential properties of sulphur for operation, including that of subliming, substantially excluding from the interior s ace of the container above the surface 0 said liquid all 15 substances chemically reactive therewlth, and introducing into the body of said liquid below the surface thereof 'a substance which is chemically reactive therewith in such manner and in such amounts as to vaporize a substantial portion of the liquid by the heat of reaction of the substance with the reacting portion of the liquid.

In testimony whereof, I aflix my signature.

LOWRY GILLETT.

CERTIFICATE OF CORRECTION.

Patent No. 1,832,013. Granted November 17, 1931, to

LOWRY GILLETT.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 4, line 123, claim 1, strike out the words "presence of"; page 5, line 113, claim 13, after the word "head" insert the word positioned, and line 117, same claim, after the comma and before the word "said" insert the article the; and that the said Letters Patent should be read with these corrections therein that the same may coniorm to the record of the case in the Patent Office.

Signed and sealed this 9th day of February, A. D. 1932.

M. J. Moore. (Seal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

Patent No. 1,832,013. Granted November 17, 1931, to

LOWRY GILLE'I'T.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 4. line 123, claim I, strike out the words "presence of"; page 5, line 113, claim 13, after the word "head" insert the word positioned, and line [17, same claim, after the comma and before the word "said" insert the article the; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 9th day of February, A. D. I932.

M. J. Moore.

(Seal) Acting Commissioner of Patents. 

